Term
| What are the two functions of the skin? |
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Definition
| Protection and sensory (sensation) |
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Term
| Where are the receptors for somatosensation located? |
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Definition
- Hair follicle
- Meisner's corpuscles
- merkel disks
- Pacinian endings
- Ruffini endings
- Free nerve endings
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Term
| How do they differ from each other? |
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Definition
Know and understand concepts:
Different rates of adaptation, different receptive field sizes. Also they respind preferentially to different types of stimuli. |
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Term
| How are receptive fields related to the size of somatosensory cortex? |
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Definition
| Merkels disk- small/sharp border; Ruffini Corpuscle- large/diffuse border; Meissners Corpuscle- large/diffuse border; Pacinian Corpuscle- small/sharp border |
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Term
| Do you think you use the same types of receptors for reading braille and enjoying a massage? Why or why not? |
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Definition
| The receptors in the fingers that help you do fine discrimination (merkel and meissner) are not found all over the body, at least not as densely, so when your shoulders are being rubbed, for example, you are not necessarily using those receptors to feel it. Also, different receptors respond to different types of stimulation (like the different type produced from running your fingers across Braille versus having your shoulders massaged). |
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Term
| How do pacinian corpuscles work? |
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Definition
Force--> neuron's membrane is deflected-->channels become leaky to sodium--> EPSP
only sudden or vibrating force can deflect membrane
Onion- like outer membrane provides mechanical support so it is resistant to gradual or constant pressure |
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Term
| Where is the pathway that somotosensory info takes to the brain? |
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Definition
- Spinal cord
- medulla
- midbrain
- thalamus
- ventricle
- cerebral cortex
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Term
| Difference between general touch and pain/temperature? |
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Definition
| Both enter the spinal cord in the dorsal horn. Touch doesn't synapse and travels up to junction b/t spinal cord and medulla. Then crosses, then thalamus then cortex. Pain and temp synapses as soon as it enters cord. Then crosses to other side and ascends to thalamus, then cortex. |
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Term
| What is the function of pain? |
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Definition
| To alert us of bodily harm! |
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Term
| What types of receptors are stimulated by noxious stimuli? |
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Definition
- Mechanical: activated by strong stimuli(pinch, sharp objects) Via A-delta fibers
- Thermal: activated by noxious heat or cold & strong mechanical; via A-delta fibers
- Polymodal: activated by noxious mechanical, heat, cold, chemical; slow dull or aching pain. Via non-myelinated C fibers
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Term
| What does the brain code for increasing intensity of pain? |
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Definition
| more brain areas are activated |
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Term
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Definition
| A painkilling substance (similar to opioids) made by the body in response to pain. |
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Term
| When are endorphins released? |
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Definition
| inescapable pain, sec, runner's high, and enjoyable music. |
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Term
| How are endorphins related to morphine? |
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Definition
| Uses the same receptor as morphine (opiates) |
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Term
| What is the gate theory of pain? |
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Definition
| pain is a function of the balance between the information traveling into the spinal cord through large nerve fibers and information traveling into the spinal cord through small nerve fibers. Remember, large nerve fibers carry non-nociceptive information and small nerve fibers carry nociceptive information. If the relative amount of activity is greater in large nerve fibers, there should be little or no pain. However, if there is more activity in small nerve fibers, then there will be pain |
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Term
| Where do opioid drugs work in the CNS? |
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Definition
| periaqueductal gray area of the midbrain |
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Term
| How does the periaqueductal gray (PAG) modulate pain perception? |
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Definition
| It contains lots of opioid receptors. PAG gets noxious stimuli, PAG can activate descending pain control pathway to block incoming "pain" message. |
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Term
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Definition
Transcutaneous Electric Nerve Stimulation
- stimulates afferent myelinated fibers
- Activates inhibitory circuits in SC
- Nerve impulse transmission reduced
- Decreased perception of pain
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Term
| How do local anesthetics work? |
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Definition
| Block the conduction of nerve impulses in a localized/discrete area (sodium channel blocker) |
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Term
| How do NSAIDS(anti-inflamatories) work? |
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Definition
| Blocks release of histamine, NGF, and other chemicals. |
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Term
| What is evidence that endorphins are involved in the placebo effect? |
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Definition
| There is increased activity in the periaqueductal gray. |
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Term
| What are hyperalgesia and allodynia? |
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Definition
Hyperalgesia: Stimuli that are normally mildly uncomfortable become very painful.
Allodynia: normally innocuous stimuli become very painful (swallowing w/ a soar throat) |
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